Electric resistance heating elements



May 26, 1964 A. c. BoGGs ELECTRIC RESISTANCE HEATING ELEMENTS I Filed Jan. 1'7, 1961 2 Sheets-Sheet 1 Arrow/5;

May 26, 1964 A. c. BoGGs 3,134,956

ELECTRIC RESISTANCE HEATING ELEMENTS Filed Jan. 1'7, 1961 2 Sheets-Sheet 2 2j if j INVENTOR. ALBEN C.BOGG5 PIGA. j

f B1G .United States Patent Oiice 3,134,956 Patented May 26, 1964 3,134,956 ELECTRIC RESISTANCE HEATING ELEMENTS Alben C. Boggs, Pittsburgh, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa. Filed Jan. 17, 1961, Ser. No. 83,275 4 Claims. (Cl. 3318-273) The present invention relates to electric resistance heating elements, more particularly to elements of the type having a resistor conductor carried on the exterior of a ceramic-like body, and the principal object of the invention is to provide new and improved methods and articles `of the character described.

Although it has long been common practice in the manufacture of electric resistance heaters to provide relatively heavy, rigid terminal conductors at respective ends of the relatively fragile resistor conductor to which terminals the electrical circuit connections can be made, problems frequently arise in eiectuating satisfactory electrical connections between the resistor and the terminals. Such problems arise in part because of the design of the heating element and in part because of the very delicate nature of the resistor in the lower wattage elements.

While some prior art designs and methods have resulted in heaters which were functionally satisfactory, most have been relatively expensive to manufacture; hence their use was unduly limited.

The present invention provides electric heaters which can be manufactured at low cost without impairing heater eiciency. Other advantages will readily become apparent from a study of the following description and from the drawings appended hereto.

In the drawings accompanying this specification and forming a part of this application there is shown, for purpose of illustration, an embodiment which the invention may assume, and in these drawings:

FIGURE 1 is a view in longitudinal section of an eleotric resistance heater constructed in accordance with the present invention,

FIGURE 2 is an enlarged, fragmentary perspective view of a detail seen in FIGURE 1,

FIGURE 3 is an enlarged perspective View of another detail seen in FIGURE 1 but at a preliminary stage of assembly,

FIGURES 4, 5, and 6 are views similar to FIGURE 1 but during preliminary stages of assembly, and

FIGURE 7 is an enlarged, fragmentary view similar to FIGURE 6 but showing certain parts at one stage of assembly in full lines and at another stage of assembly in phantom lines.

With reference to FIGURE 1, the present heater comprises an elongated, cylindrical core 10 of electric-insulating, heat-resistant material, having in spaced, side-by-side relation a pair of through openings 11 later to be more fully described. Extending through respective openings 11 are terminal conductor pins 12 and 13 which, in the position of parts shown, project a relatively small amount beyond the right end of core 10 and a relatively large amount beyond the left end of the core. Pin 12 has an upset portion 14 adjacent its right hand end which provides an abutment engaging the adjoining core end to prevent Withdrawal of pin 12 from the core by movement of the pin to the left,

Wound upon the exterior of core 10 from end to end thereof is a resistor conductor wire 15 whose ends are Welded or otherwise electrically connected to clips 16 later to be described in greater detail. Each clip 16 is disposed at a respective end of the core 10 and each is welded at 17 or otherwise electrically connected to respective terminal pins.

Surrounding core 10 is a sleeve 18 which is presently formed of a material similar to that of the core. Such sleeve is somewhat longer than the core to extend beyond respective ends thereof as shown. Pins 12 and 13 may project beyond the left hand end of sleeve 18 any desired distance for connection to a source of electrical energy. In the present embodiment, insulating tubes 19 surround the projecting left ends of respective terminal pins to insure against shorts and grounds.

Provision is made for closing respective ends of sleeve 18 and, as herein illustrated, each end of the sleeve is iilled with a body of plastic, electric-insulating, heat-resistant material 20 which sets to a rock-like hardness to not only close the sleeve ends but to also retain the parts rigidly assembled. Any commercially Iavailable air-set cement would be suitable for this purpose. Note that since the ends of the tubes 19 are embedded in the adjoining material 20, they too will be permanently retained in place.

The body 10 and the clips 16 will now be described in greater detail and, since both clips are identical, only one will be specifically referred to. Referring to FIGURE 2, each body aperture 11 is cross-sectionally conligurated to provide an arcuate-portion 21 for closely engaging a respective round terminal pin and a rectangular portion 22 for a purpose to be seen. As illustrated, aperture portions 22 are located adjacent the periphery of the body.

With reference now to FIGURE 3, clip 16 is presently formed of a length of strip metal folded over at 23 to form a double thickness and then bent to an L-shaped conguration. As will be observed in FIGURE 5, portion 23 of each clip is adapted to be inserted in a respective aperture portion 22 from opposite ends of the body to project radially outwardly of the latter. It is to be understood that the aperture portions 22 are proportioned to closely receive the clip portions 23.

Assembly of the heater will preferably proceed as follows: Clips 16 will be inserted in respective body aperture portions 22, as illustrated in FIGURE 4, and each will be bent so that a leg 24 thereof overlies the exterior of the body, One end of resistor 15 will next be welded or otherwise electrically connectedt to the leg 24 of a clip at one end of the body and the resistor then wound upon the exterior of the body from such one end to the other as seen in FIGURE 5. The resistor adjacent such other body end will then be Welded or the like to the leg 24 of the other clip.

Terminal pins 12 and 13 will then be inserted in respective body aperture portions 21, as seen in FIGURE 6, With the upset portion of pin 12 in abutting relation with the adjoining body end. Each clip leg 25 may then be straightened to lie along its terminal pin as seen in full lines in FIGURE 7 and in the present embodiment, such leg is spot-welded to its pin at 17.

With the pins, clips and resistor assembled with the body 10 as above described, the sleeve 18 will be slipped over the body to extend beyond the ends thereof. Note that abutment 14 on pin 12 prevents withdrawal of the latter from the body by movement to the left while clip 16 on the pin 13 serves the same purpose for the latter pin. Tubes 19 will now be positioned over the outwardly projecting ends of the terminal pins and both ends of the sleeve then lled with the material 20 in plastic form. Upon hardening of the material 20 to a rocklike hardness, the heater is ready for use following connection of the projecting ends of the terminal pins to a suitable source of electrical energy.

In View of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated 3 that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. An electric heating element, comprising a dielectric core having a pair of longitudinal openings therethrough, each opening in crosssection having a circular portion and a slot tangential to and communicating with said circular portion, a pair of cylindrical metallic terminal pins closely fitting in and extending through the circular portion of `respective openings, yone terminal pin having a sheet-metal clip secured thereto and having a first portion lying along 'the surface thereof and closely fitting within the slot of one opening a one end of said core and having a resistor wire receiving portion abutting said core one end to limit insertion of said first portion to only an end part of said one opening, and the other terminal pin having a sheet-metal clip secured thereto and having a first portion lying along the surface thereof and closely tting within the slot of the other opening at the opposite end of the core and having a resistor wire receiving portion abutting said core opposite end to limit insertion of its respective irst portion to only an end part of said other opening, and a resistor Wire having one end electrically connected to the receiving portion of the clip on said one terminal pin and wound around said core and having its opposite end electrically connected to the receiving portion of the clip on said other terminal p1n.

2. vAn electric heating element, comprising a dielectric core having a pair of longitudinal openings therethrough, each opening in cross-section having a circular portion and a slot tangential to and communicating with said circular portion, a pair of cylindrical metallic terminal pins closely fitting within and extending through the circular portion of respective openings, one terminal pin having a sheet-metal clip secured thereto and having a portion lying along the surface thereof and closely fitting within the slot of one opening at one end of said core, and the other terminal Vpin having 'a sheet-metal clip secured thereto and lhaving a portion lying along the surface thereof and closely fitting within the slot of the other opening at the opposite end of said core, a resistor wire having one end electrically connected to the clip on said one terminal pin and wound around said core and having its opposite end electrically connected to the clip on said other terminal pin, a dielectric sleeve surrounding said core, end portions of said terminal pins extending outwardly of said sleeve, dielectric tubes surrounding the outwardly extending end portions of said terminal pins, and dielectric cement closing the ends of said sleeve yand disposed about said dielectric tubes to hold the latter in position.

3. An electric heating element, comprising a dielectric core having a longitudinal opening therethrough, a terminal pin tting closely Within and extending through said opening with its opposite ends projecting beyond the ends of said core, one end of said terminal pin having an enlargement abutting the `adjacent end of said core to restrict movement of said terminal pin toward the opposite core end, and the other end of said terminal pin having a terminal clip rigidly secured to it and abutting the opposite core end to restrict movement of said terminal pin toward said adjacent end of said core, and a resistor wire on said core and having electrical connection with Said terminal clip.

4. The construction of claim 3 and further including a second terminal pin extending through a second longitudinal opening in said core and having a terminal clip at said adjacent end of said core, said resistor wire having its opposite ends electrically connected to said terminal clips and its intermediate portion wound about said core whereby said resistor wire and said terminal pins are connected in series relation.

References Cited in the file of this patent UNITED STATES PATENTS 1,525,831 Steiner et al Feb. 10, 1925 1,608,005 Schoeppler Nov. 23, 1926 2,011,555 Burlingame Aug. 13, 1935 2,388,667 Bugler et al Nov. 13, 1945 2,527,026 Mucher Oct. 24, 1950 2,976,509 McFaddan Mar. 21, 1961 FOREIGN PATENTS 906,769 France May 28, 1945 813,465 Great Brit-ain May 13, 1959 858,322 Great Britain Jan. l1, 1961 

1. AN ELECTRIC HEATING ELEMENT, COMPRISING A DIELECTRIC CORE HAVING A PAIR OF LONGITUDINAL OPENINGS THERETHROUGH, EACH OPENING IN CROSS-SECTION HAVING A CIRCULAR PORTION AND A SLOT TANGENTIAL TO AND COMMUNICATING WITH SAID CIRCULAR PORTION, A PAIR OF CYLINDRICAL METALLIC TERMINAL PINS CLOSELY FITTING IN AND EXTENDING THROUGH THE CIRCULAR PORTION OF RESPECTIVE OPENINGS, ONE TERMINAL PIN HAVING A SHEET-METAL CLIP SECURED THERETO AND HAVING A FIRST PORTION LYING ALONG THE SURFACE THEREOF AND CLOSELY FITTING WITHIN THE SLOT OF ONE OPENING A ONE END OF SAID CORE AND HAVING A RESISTOR WIRE RECEIVING PORTION ABUTTING SAID CORE ONE END TO LIMIT INSERTION OF SAID FIRST PORTION TO ONLY AN END PART OF SAID ONE OPENING, AND THE OTHER TERMINAL PIN HAVING A SHEET-METAL 